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Old 23rd February 2012, 06:02 PM   #561
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Quote:
Originally Posted by koja View Post
You guys lost me with all these changes.

Andy,

the first time I checked with you about the dimensions for a V2 after cutting off the two pairs for V3 it looked good forme (177mm length). Now that you made a dedicated V2 combo board you extended it to 250mm overall (it does not fit my 9" sink any more).

A lot of length seems to be lost just at the very ends to the pcb mounting and inscription. Can all that be brought inward between the first and the second output pair and the board made shorter again? I would much appreciate it!

cheers,
K.
If we put the output transistors too close the heat won't spread as evenly on the heatsink.
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Old 23rd February 2012, 06:25 PM   #562
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I see that Peter just ran out of his PS boards, but if he has more made would there be any reason not to just use those? They accept 50mm caps and are modular, so if you want to use more caps you can just add more boards.
Universal Power Supply PCB
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Old 23rd February 2012, 06:31 PM   #563
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Originally Posted by PKI View Post
Excuse me
Euh, the diode supercharger ? (and detail stuff)

30W and 4 ohm have no need for a pimped ride, imo.
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Old 23rd February 2012, 07:15 PM   #564
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Hi there!

I was thinking about running F5 Turbo with 75V rails and 8 2SK1530/2SJ201 pairs per channel, each output device with 100mA bias. So I ask whether the lower bias is adequate for the design and also whether the first stage board will allow paralleling two output boards. I already own the transistors and I'm looking for a design in which I can use them. Any suggestions are highly appreciated.

Thanks in advance
Daniel
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Old 23rd February 2012, 07:59 PM   #565
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Originally Posted by Daniel(Del) View Post
Hi there!

I was thinking about running F5 Turbo with 75V rails and 8 2SK1530/2SJ201 pairs per channel, each output device with 100mA bias. So I ask whether the lower bias is adequate for the design and also whether the first stage board will allow paralleling two output boards. I already own the transistors and I'm looking for a design in which I can use them. Any suggestions are highly appreciated.

Thanks in advance
Daniel
How much power do you really need? 75v rails seems quite a lot! Nelson's recommendation is 32 for v2 and higher for v3 but I would say maybe 45max. As far as I understand, it is better to have a lower voltage and higher bias current to go deep into class A.
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Old 23rd February 2012, 08:16 PM   #566
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Originally Posted by MASantos View Post
How much power do you really need? 75v rails seems quite a lot! Nelson's recommendation is 32 for v2 and higher for v3 but I would say maybe 45max. As far as I understand, it is better to have a lower voltage and higher bias current to go deep into class A.
He plan on using 32 outputs .... If so I like with 50 v rails ....
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Old 23rd February 2012, 09:54 PM   #567
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Originally Posted by MASantos View Post
quite a lot!
A1837/C4793 are good for 230V, with the 25V limit of the J74 good for +75V rails as is now.
Alter the voltage divider of the cascode devices for higher rails, and he could go to 125V, if not for the 100V (90V safer) limit of the output MOSFETs.

Bare in mind that F5 is common source : Fqa12p20 Fqa19n20c Discontinuation
With 8 pairs of those, logical choice is to use parallel input JFETs (me would pick Violets with aircon)
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Old 23rd February 2012, 10:21 PM   #568
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Originally Posted by jacco vermeulen View Post
A1837/C4793 are good for 230V, with the 25V limit of the J74 good for +75V rails as is now.
Alter the voltage divider of the cascode devices for higher rails, and he could go to 125V, if not for the 100V (90V safer) limit of the output MOSFETs.

Bare in mind that F5 is common source : Fqa12p20 Fqa19n20c Discontinuation
With 8 pairs of those, logical choice is to use parallel input JFETs (me would pick Violets with aircon)
Jacco can V3 really work with 8 prs/ch .....
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Old 23rd February 2012, 10:30 PM   #569
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Do the math, about 100KHz bandwidth with single inputs.
Double up the barrels : 200Khz
(some folks in this joint still enjoy 50ish. Burp !)

100mA bias, Burp too !
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Old 23rd February 2012, 10:40 PM   #570
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